Download (.pdf) An Approach to Comparing Nations for Inclusion of Studies in Health-based Systematic Literature Reviews
Background: To develop and demonstrate a systematic approach for comparing nations, for the purpose of deciding... more Background: To develop and demonstrate a systematic approach for comparing nations, for the purpose of deciding whether to include or exclude studies in a systematic review of a health research question pertinent to the Canadian population. Results: a template of nine criteria was developed, including both sociodemographic and systemic indicators, and was applied to 68 jurisdictions, of which 19 were deemed sufficiently comparable to Canada to be included in the review. Conclusions: Subsequent systematic reviews, regardless of which nation is ultimately the reference population, should employ a similar process, with indicators and characteristics specific to the research questions, to ensure that political, economic, historical or ethnic biases are not influencing the selection or rejection of relevant papers.
A Comparison of Methods for Measuring Socio-economic Status by Occupation or Postal Area
Seven methods of estimating socio-economic status (SES) were compared, including four based on data specific to... more Seven methods of estimating socio-economic status (SES) were compared, including four based on data specific to individuals (Blishen, Pineo-Porter, British Registrar General, Hollingshead) and three based on the average characteristics of the postal code area in which people live (income alone, education alone, income and education combined). Data from the files of 151 patients undergoing in vitro fertilization were used. The four individual scales were highly correlated among themselves (Spearman's correlation coefficient between 0.6 and 0.9) but only moderately correlated with the measures based on postal code (Spearman's correlation coefficient between 0.2 and 0.3).
Driving deaths and injuries post-9/11
Objectives: In the days immediately following the terror attacks of 9/11, thousands of Americans chose to drive rather... more Objectives: In the days immediately following the terror attacks of 9/11, thousands of Americans chose to drive rather than to fly. We analyzed highway accident data to determine whether or not the number of fatalities and injuries following 9/11 differed from those in the same time period in 2000 and 2002. Methods: Motor crash data from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System were analyzed to determine the numbers and rates of fatalities and injuries nationally and in selected states for the 20 days after September 11, in each of 2000, 2001, and 2002. Results: While the fatality rate did not change appreciably, the number of less severe injuries was statistically higher in 2001 than in 2000, both nationally and in New York State. Conclusions: The fear of terror attacks may have compelled Americans to drive instead of fly. They were thus exposed to the heightened risk of injury and death posed by driving. The need for public health to manage risk perception and communication is thus heightened in an era of global fear and terrorism.
A Bayesian mixture modeling approach for assessing the effects of correlated exposures in case-control studies
Frank de Vocht, Nicola Cherry, jon Wakefield
Predisposition to a disease is usually caused by cumulative effects of a multitude of exposures and lifestyle factors... more Predisposition to a disease is usually caused by cumulative effects of a multitude of exposures and lifestyle factors in combination with individual susceptibility. Failure to include all relevant variables may result in biased risk estimates and decreased power, whereas inclusion of all variables may lead to computational difficulties, especially when variables are correlated. We describe a Bayesian Mixture Model (BMM) incorporating a variable-selection prior and compared its performance with logistic multiple regression model (LM) in simulated case–control data with up to twenty exposures with varying prevalences and correlations. In addition, as a practical example we re analyzed data on male infertility and occupational exposures (Chaps-UK). BMM mean-squared errors (MSE) were smaller than of the LM, and were independent of the number of model parameters. BMM type I errors were minimal (less than or equal to1), whereas for the LM this increased with the number of parameters and correlation between exposures. The numbers of type II errors were comparable. Re analysis of Chaps-UK data demonstrated more convincingly than by using a LM that occupational exposure to glycol ethers and VOCs are likely risk factors for male infertility. This BMM proves an appealing alternative to standard logistic regression when dealing with the analysis of (correlated) exposures in case–control studies.
Infection rates of Triatoma protracta (Uhler) with Trypanosoma cruzi in Southern California and molecular identification of trypanosomes
Published in 'The American Journal of Tropical Medicine and Hygiene'
We report Trypanosoma cruzi infection rates of the native kissing bug Triatoma protracta in southern California. The... more We report Trypanosoma cruzi infection rates of the native kissing bug Triatoma protracta in southern California. The rates are within the historically reported range, but differ significantly between the two sites (19% in Escondido and 36% in Glendora). Identification of T. cruzi in T. protracta was conducted for the first time by using partial 18S ribosomal RNA and 24Sα ribosomal RNA sequences. Incongruence of 24Sα ribosomal RNA phylogeny with current T. cruzi genotype classification supports non-clonality of some T. cruzi genotypes.
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Mammalian Diversity, Evolution and Potential Reservoir of Diseases. 2011
SOCIAL AND ECOLOGICAL DIMENSION OF INFECTIOUS DISEASES BANGKOK, 6-7 OCTOBER 2011.
Key words: Biodiversity, Diseases, Zoonosis, Climate Change, Evolution Key words: Biodiversity, Diseases, Zoonosis, Climate Change, Evolution
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Exercise intervention and inflammatory markers in coronary artery disease: a meta-analysis
Swardfager W, Herrmann N, Cornish S, Mazereeuw G, Marzolini S, Sham L, Lanctôt KL. Am Heart J 2012;163:666-676.e3
Background: Inflammatory activity plays a role in the development and progression of coronary artery disease (CAD),... more
Background: Inflammatory activity plays a role in the development and progression of coronary artery disease (CAD), and exercise confers survival benefit. We performed a meta-analysis of changes in inflammatory biomarkers over the course of exercise interventions in patients with CAD.
Methods: We searched MEDLINE, Embase, the Cochrane Collaboration, AMED, and CINAHL for studies reporting peripheral inflammatory biomarker concentrations before and after exercise interventions of ≥2 weeks in patients with CAD. Data were summarized using standard mean differences (SMD) and 95% CIs.
Results: Twenty-three studies were included. Concentrations of C-reactive protein (CRP; SMD −0.345, 95% CI −0.444 to −0.246, n = 1,466, P < .001), interleukin 6 (SMD −0.546, 95% CI −0.739 to −0.353, n = 280, P < .001), fibrinogen (SMD −0.638, 95% CI −0.953 to −0.323, n = 247, P < .001), and vascular cell adhesion molecule 1 (SMD −0.413, 95% CI −0.778 to −0.048, n = 187, P = .027) were lower postintervention. Higher total cholesterol (B = −0.328, 95% CI −0.612 to −0.043, P = .026) and higher total/high-density lipoprotein cholesterol ratios (B = −0.250, 95% CI −0.425 to −0.076, P = .008) at baseline were associated with greater reductions in CRP. In controlled studies, follow-up concentrations of CRP (SMD −0.500, 95% CI −0.844 to −0.157, nexercise/control = 485/284, P = .004), and fibrinogen (SMD −0.544, 95% CI −1.058 to −0.030, nexercise/control = 148/100, P = .038) were lower in subjects who exercised compared with controls.
Conclusion: Exercise training is associated with reduced inflammatory activity in patients with CAD. C-reactive protein and fibrinogen have provided the strongest evidence. Higher baseline CRP and adverse baseline lipid profiles predicted greater reductions in CRP.
Complémentarité et discordances entre sources textuelles et les sources archéo-anthropologiques en contexte de crises de mortalité par épidémie. Etudes de cas / Complementarity and conflicts between textual and archaeo-anthropological sources in the context of mortality crises from epidemics. Case studies
co-authored with "Dominique CASTEX (CNRS) and Philippe BLANCHARD (Inrap)", published in "Revue Archéologique du Centre de la France (RACF)", 47, 2008.
Résumé :
Longtemps sources archéologiques et textuelles ont été considérées comme complémentaires, or elles... more
Résumé :
Longtemps sources archéologiques et textuelles ont été considérées comme complémentaires, or elles apparaissent bien souvent contradictoires. Actuellement la dépendance de l’archéologie des périodes historiques vis à vis des sources écrites n’est plus vraiment de mise. Progressivement s’élabore une autre manière de concevoir l’interdisciplinarité, l’objectif n’étant plus d’aller chercher dans l’une des sources de quoi valider l’autre mais plutôt de construire en commun des objets de recherche permettant une utilisation conjointe efficace des données et une discussion des résultats. Cette démarche, indispensable à toute analyse des sites historiques, est fondamentale pour l’interprétation des crises de mortalité par épidémie du passé. Elle a sous-tendu différentes études interdisciplinaires récentes liées à des découvertes d’archéologie préventives dans le Berry comme à Bourges (Cher) et Issoudun (Indre) ainsi que des prospections en archives comme à Lignières-en-Berry (Cher). En raison de leur originalité nous souhaitons présenter ces exemples et les comparer à d’autres sites de victimes d’épidémie à l’étranger (Saint-Benoît de Prague en République tchèque et Venosa en Italie), des sites dont la quantité et la qualité de la documentation ont permis une bonne exploitation et ont d’ores et déjà fourni des premiers résultats en termes d’interprétation. Sans prétendre au traitement exhaustif de chaque site, dont certains sont encore en cours d’étude, notre propos est plus simplement de proposer une réflexion sur quelques aspects de l’archéologie des épidémies, de livrer un certain nombre de questionnements et de discuter de la faisabilité des synthèses des sources écrites et archéologiques. Nos résultats nous permettent d’ores et déjà d’apporter des éclairages nouveaux sur l’histoire des épidémies ; d’une part ils mettent en avant des aspects bien différents de ceux généralement admis en contexte de crises de mortalité (gestion maîtrisée des cadavres, intégration des morts par épidémie, etc.), d’autre part, ils nous engagent à être particulièrement vigilants quant à l’origine même des épidémies proposée par certaines sources écrites.
Abstract :
Archaeological and textual sources have long been considered complementary although they often appear contradictory. Nowadays the dependence of archaeology on written sources within historical periods is steadily being replaced by a different concept of interdisciplinarity : rather than seeking to validate one source by another, the different disciplines form a common research project so as to make efficient use conjointly of all available data and allow discussion of the results. This procedure is indispensable in all analyses of historical sites and is fundamental in the interpretation of mortality crises of the past due to epidemics. It underlies recent interdisciplinary studies linked to archaeological discoveries in Berry (France) like Bourges (Cher) and Issoudun (Indre) and archive prospections like Lignières-en-Berry (Cher). Because of their originality we wish to present these examples and to compare them with the other victims' sites of epidemics abroad (Saint Benoît from Prague to Czech Republic and Venosa in Italy), sites among which the quantity and the quality of the documentation allowed a good exploitation and already supplied first results with terms of interpretation. Without aspiring to the exhaustive treatment of every site, some of which are still in the course of study, our comment is more simply to propose a reflection on some aspects of the archaeology of the epidemics, to deliver certain number of questionings and to discuss the feasibility of the syntheses of the written and archaeological sources. Our results already allow us to bring new light to the history of epidemics; on one hand they highlight aspects very different from those generally admitted in context of crises of mortality ( mastered management of corpses, integration of the deaths by epidemic, etc.), on the other hand, they commit us to be particularly watchful as for the origin of the epidemics proposed by certain written sources.
Urinary DAP metabolite levels in Thai farmers and their families and exposure to pesticides from agricultural pesticide spraying.
Hanchenlaksh C, Povey A, O'Brien S, de Vocht F.
Introduction We conducted a biomarker study to characterise exposure to pesticides among farmers and their families in... more Introduction We conducted a biomarker study to characterise exposure to pesticides among farmers and their families in Thailand to assess the relative importance of the dermal exposure route and to identify important factors that determine exposure levels within farmers' families. Methods Sixteen farmers' families (eight vegetable and eight fruit farmers) participated in the study. Three morning spot urine samples were collected during a pesticide spraying week. Spot samples were grouped by individual and analysed for dialkylphosphate (DAP) metabolites and creatinine. Additional information on exposure and lifestyle was collected by means of questionnaires. Dermal exposure was assessed using a semi-quantitative observational method (DREAM). Results Urinary DAP levels varied 20-fold between farmers, with average (geometric mean) levels of 51.1 μg/g for vegetable and 122.2 μg/g for fruit farmers. A moderate correlation (r(s)∼0.45) was found between log(e)-transformed DREAM scores and DAP levels. Farmers' urinary metabolite levels were not correlated with those of their spouses (r(s)∼-0.30) or children (r(s)∼-0.00) collected on the same days. Detectable spouses' DAP levels were on average (geometric mean) 13.0 μg/g and those of children 7.6 μg/g. Discussion Farmers in Thailand as well as their families are exposed to pesticides in the spraying season and dermal exposure is an important route. The main route of exposure for farmers' families seems to be through transfer from the farmer to family members or contamination of the home environment, rather than family members helping or playing on the farm. Showering or washing immediately after pesticide spraying greatly reduces the potential exposure of family members to pesticide residues.
Exposure to rubber process dust and fume since 1970s in the United Kingdom; influence of origin of measurement data.
Agostini M, de Vocht F, van Tongeren M, Cherrie JW, Galea KS, Kromhout H.
The objective of this study was to compare measured concentrations of rubber process dust and rubber fume originating... more
The objective of this study was to compare measured concentrations of rubber process dust and rubber fume originating from different sources in the British rubber manufacturing industry. Almost 8000 exposure measurements were obtained from industry-based survey results collected by the British Rubber Manufacturers' Association (BRMA), and covering the years 1977 to 2002, and from a series of small surveys contained in the Health and Safety Executive's (HSE) National Exposure Database (HSE-NEDB) from 1980 to 2002. The analysis investigated temporal trends in the exposure concentrations and the underlying main factors responsible for these changes. Analyses were carried out using hierarchical linear mixed effects models. Average personal exposures to rubber process dust and rubber fumes were respectively a factor 2 and 4 higher for the HSE-NEDB data when compared to data originating from the industry (BRMA data). Personal exposure to rubber process dust decreased on average by 4.1% (95% CI 4.7-3.6) annually for the BRMA data and slightly less at 2.3% (95% CI 5.2-0.7%) per annum for the HSE-NEDB data. Personal exposure to rubber fume also showed a downward temporal trend of 2.9% (95% CI 3.6-2.3%) and 4.8% (95% CI 7.4-2.1%) annually for the BRMA and HSE-NEDB data, respectively. These trends differed considerably between departments. No major changes in the estimated temporal trends in exposure concentrations were observed after including the presence of local exhaust ventilation in the models for any department in the BRMA and HSE-NEDB datasets. Lack of information on the quality and status of the local exhaust ventilation is the most likely explanation for this. In conclusion, even though there were relatively similar downward time trends in both rubber process dust and fume concentrations in both datasets, the source of exposure data was an important determinant of average exposure concentrations present in the British rubber manufacturing industry. Lack of detailed auxiliary information on company size, reason for sampling, measurement strategy and other potentially important determinants of exposure prevented an explanation for the observed differences in exposure level.
Assessment of dermal exposure to bitumen condensate among road paving and mastic crews with an observational method.
Agostini M, Fransman W, Vocht FD, Joode BV, Kromhout H.
To assess dermal exposure to bitumen condensate among road pavers and indoor mastic workers in multiple crews using a... more
To assess dermal exposure to bitumen condensate among road pavers and indoor mastic workers in multiple crews using a semi-quantitative observational method [DeRmal Exposure Assessment Method (DREAM)].
METHODS:
Two skilled observers assessed dermal exposure to bitumen condensate among 85 asphalt workers from 12 crews from nine companies active within four European countries using the DREAM methodology, which produces an estimate of exposure expressed in dimensionless DREAM units. Both observers independently evaluated each crew member's job (N = 14 jobs) for road paving and mastic applications. Potential and actual dermal exposures were estimated for hands and for the rest of the body separately, taking into account the effect of protective clothing. To evaluate the reproducibility of the observational method intra-class correlation coefficients (ICCs) were estimated. The exposures in DREAM units were modelled using linear mixed models to estimate average relative scores for each job. Correlations between dermal exposure parameters were evaluated by estimating Pearson correlation coefficients.
RESULTS:
A total of 170 observations were completed by two observers independently (n = 118 and n = 52 for 59 road pavers and 26 mastic workers, respectively) in 11 days. The mean ICCs (for potential and actual exposure in DREAM units) varied between 0.74 and 0.80 with values for actual units being slightly higher. Geometric mean potential dermal exposure units of mastic workers were higher than for road pavers (factor 3 for hands and factor 4 for rest of the body). Differences for actual dermal exposure units were smaller for hands (factor 2) and larger for actual exposure units of rest of the body (factor 5). Differences in dermal exposure at the hands between jobs within a paving crew were much larger than between jobs within a mastic crew. Within paving crews, a consistent pattern for all exposure units emerged with 'screed man' and 'raker' as the two highest exposed jobs. Within mastic crews, 'driver dumper truck' and 'spreader of mastic' were scored as the two jobs with the highest exposure units. Potential and actual exposure units were highly correlated. Hands were more profoundly exposed than the rest of the body, with transfer from contaminated surface to the hands as the most important route.
CONCLUSIONS:
DREAM observations were reproducible and showed a consistent dermal exposure pattern among the observed crews. The study provided a clear picture of dermal exposure among road pavers and indoor mastic workers, with the mastic workers being considerably more highly exposed. The most important route of exposure appeared to be transferred from contaminated surfaces to the hands.
An epidemiological model of dengue fever including second infection stage in human host.
"Published in 'XVI Simposio Internacional de Métodos Matemáticos Aplicados a las Ciencias'"
Nowadays 2.5 billion Persons live in areas where the risk of dengue fever exists.
Furthermore, the disease could... more
Nowadays 2.5 billion Persons live in areas where the risk of dengue fever exists.
Furthermore, the disease could enlarge its geographical range due to variation in climatic patterns. Therefore, accurate models are needed to control and understand the ecological relationships giving place to this and other arthropod borne diseases.
We developed amodified susceptible-infectious-removed (SIR)model of Dengue cross-
infection between humans and mosquitoes, incorporating an irreversible lost of initial susceptibility and a second infection stage in human host, according to the immuno- logical and molecular dynamics of Dengue and Dengue Hemorrhagic Fever (DHF). We obtained the disease reproduction number R0 and showed that the second stage infec- tion of human host would be an important consideration for the emergence of DHF and serotypes recombination among dengue virus population
Assigning exposure to pesticides and solvents from self reports collected by a computer assisted personal interview and expert assessment of job codes: the UK Adult Brain Tumour Study
co-authored, published in Occupational and Environmental Medicine
Objectives: To compare assignment of occupational pesticide and solvent exposure using self-reported data collected by... more
Objectives: To compare assignment of occupational pesticide and solvent exposure using self-reported data collected by a computer assisted personal interview (CAPI) with exposure based on expert assessment of job codes. To discuss the advantages and disadvantages of using a CAPI to collect individual occupational exposure data.
Methods: Between 2001 and 2004, 1495 participants were interviewed using a CAPI for a case-control study of adult brain tumours and acoustic neuromas. Two types of occupational data were collected: (1) a full history, including job title from which a job code was assigned from the Standard Occupational Classification; and (2) specific details on pesticide and solvent exposure reported by participants. Study members’ experiences of using the CAPI were recorded and advantages and disadvantages summarised.
Results: Of 7192 jobs recorded, the prevalence of self-reported exposure was 1.3% for pesticides and 11.5% for solvents. Comparing this with exposure expertly assessed from job titles showed 53.6% and 45.8% concordance for pesticides and solvents respectively. Advantages of the CAPI include no data entry stage, automatic input validation, and a reduction in interviewer bias. Disadvantages include an adverse effect on study implementation as a consequence of resources required for programming and difficulties encountered with data management prior to analysis.
Conclusions: Different methods of exposure assessment derive different exposure levels for pesticide and solvent exposure at work. Agreement between self-reported and expert assessment of exposure was greater for pesticides compared to solvents. The advantages of using a CAPI for the collection of complex
data outweigh the disadvantages for interviewers and data quality but using such a method requires extra resources at the study outset.